huygens



UNITED 'STATES PATENT OFFICE. r

GEO. W. O. HUYGENS, OF ST. LOUIS, MISSOURI, ASSIGNOR T0 HIMSELF, CHAS.BNDER,

AND D. F. TIEDEMAN.

BRIDGE.

Sbecificatiori of Letters Patent No. 14,584, dated April 1, 1856.

T0 all whom z't may concem:

Be it knowvn that I, GEORGE W. O. HUY- GENS, of St. Louis, in the Stateof Missouri, have invented a new and Improved Mode of Constructing aBridge, with the Object of Preventing Vibration.v

In order to explain fully the principle and the character by which it isdistinguished from other inventions, do I proceed to state that myinvention is based on the principle, of compensating the result of theelastic action in the material, by compensating the result ofcompression in the material by its own action, using for that purposethe compensated effect of compression only; which compression isoriginated from the pressure caused by the loads on the floor of thebridge; said compression is forced to divide itself in two compressiveforces, the final results of which are caused to be in two directions,which.are directly opposed to eaoh other, while in the same time, saidfinal results are cased to be perfectly equal in intensity; themechanical result of such forces, when tied together is rest; theyannihilate each other; in this way the effect of compression iscompensated by its ovvn effort, Whi0h explains fully the meaning of thatwhich is here designated by the terms, of the principle of compensatingthe result of the elastic actions in the material. by using thecompensated effect of compression only.

This prinoiple as here explained, constituting the base of my invention,above mentioned, distingnishes its character from other inventionsaiming at the same object; like such is claimed for certain improvedsuspension bridges, or like is claimed for certain improved bridges,which are constructed with the aroh-principle and suspension principlecombined in one; or like is claimed for certain improved bridges, whichare constructed, with the arch principle and girder principle combinedinone; all the mentioned improved bridge principles, use tension alone orpartially, and claim a neutralizing eflect, conseqnent on their combinedchamoter, but their object is always to neutralize the. compression ofmaterial by the tension of material, or the resistance of materialagainst compression by the resistance of material against tension, andthey claim that as their invention, without mentioning bowever theprinciple of compensation of the results of elasticity, or contemplatingany measures to make said compressive and tensive forces act by theirfinal results in opposed directions, or to make the results of saidforces equal in intensity while opposed in direction, in order to efiecta mutual compensation, and without mentioning any object of such anatureas preventing vibration, it being a general feature of the said improvedbridge systems, to limit their object to nentralization like abovementioned, in order to produce more stiflness with less material, quitedifferent from preventing vibration, and specially difierent by themechanical character of the principles brought in application, whichdiflerence is significai1tly represented by the word tension; and by theabsence of the terms equality of intensity.

In order to explain fully, the mode in which I have contemplated theapplication of the principle, which constitutes the base of myinvention, do I proceed to state that:

I originate said two compressive forces, which this pr1nciple calls for,by means or arches; 1, which arches are constructed following adetermined special proportion, in regard to the respective amount oftheir material; 2, which arches are arrangedin parallel vertical planes,with their curve reversed on each other; 3, which arches are providedvvith resting points ofiering their resistance or leverage in differentdirections,v

in such a manner, that those arches, *having their curve pointingupward, receive their leverage in one direction, and those having theircurve pointing downward, receive their leverage in another direction; 4,which arches are not connected or conjoined by means whatever in theircrossing points;

the object of my invention to be obtained,

viz: preventing vibration, by the application of the above mentionedprinciple by using the compensated eifect of compression only; inconsideration of which I call this bridge a compensating bridge.

The compensating bridge consequent on the peculiar mode in whichvibration is prevented in it, offers the advantage of not being subjectto alteration of its shape nor of the level of its fioor, when underpressure, which will allow cars and locomotives to pass over its fiooruncler full speed, without incurring the risk of being thrown off therails, by undulatory motions in the fioor; the compensating bridgeoffers the advantage of less wear and tear of the material of itsconstruction, incident to the distortions of uncompensated results ofelastic act-ions in the material and consequent vibration of thebridges; the absence of vibration in the compensating bridge, Will allowto save a great amount of material, which is used in other bridgesystems, above the demand of tenacity,avith a view to oppose and combatby the thickness of the parts, the uncompensated result of elasticityand consquent Vibrafion of the whole; which insures to the compensatingbridge the advantage of superior lightness, and the consequent facilityof building much larger spans than is possible to reach with heavierbridges; all of which combined insures to the compensating bridge theadvantage of economy, and makes it the cheapest of all known bridges, byfrom forty to sixty per cent.

I do hereby declare that the following is a full and exact descriptionof my invention, reference being had to the accompanying drawings and tothe letters of reference marked thereon.

1. The nature of my invention consists in providing a bridge instead ofWhich an upper chord, with a certain number of arches, in no case lessthan six, but more in proportion. The span exceeds (200) two hundredfeet; in the latter case the total number of arches becomes'a matter ofindividual judgment, only the said number should always belong to thatclass, Which are divisionable by the number three, withont any restremaining; the reason for this lies in the necessity to have always onethird ofthe total number of arches, with their curve pointing upward,like those marked A and B, the 'remaining two thirds with their curvereversed on the former pointed downward like those marked a, b, c, d,al. The proportion Which should exist, between the amount and theirmaterial, is found by using the formula in which V represents theziggregate amount of the material contained in the upper arches, 'v thatamount in the lower arches, P the strain which would happen in the loWerarches if they were alone unaided by the upper ones, p the actual strainwhich happens in the upper arches. The reason for this specialproportion lies in the neCes sity called for by the principle to makethe result of the compressive forces in the upper and lower arches equalin its intensity, which could never happen if the momentums of theelastic compression, consequently the elastic power, of the upper andlower arches, were not made to be equal, and this is done by the saidproportion, by Which the amounts are brought in inverted ratio to theelastic efforts on the fiber of the materal. The lower arches are to beconstructed with an increased cross section toward the middle, theincrease to be in direct ratio to the decrease in distance to the fioor,in order to oifer the required resistance against the compressing force.

2. The arches are arranged in parallel and vertical planes with theircurve reversed on each other. The object of this arrange ment is toprevent the arches whose curve is reversed on each other, to intersector meet each other bodily in any point, and to enable them to cross eachother without conjoining, (et) it being required that there should existno connection whatever between the upper and lower arches in theircrossing points; the reason for this lies in the prin ciple whichrequires tWo compressive forces; now it is evident that if the upper andlower arches had a point common to them, the consequence would be, thatthe lateral pressure of the upper arches would plant itself over in thelower arches and cause their immediate tension; besides by having apoint in common would cause the upper and lower arches to intermix theirrespective actions, and make it therefore' impossible to obtain fromthem results, Which are equal in intensity, like is called for by theprinciple. The reason why the lower arches have their curves reversed tothe upper ones lies in necessity imposed by the principle to create twoforces in those arches the results of which are to act in directionsdirectly opposed to each other, that'is the created tendency to curveapart or asunder, which never could exist if the arches were placed withtheir curve running parallel.

3. The arches are provided with resting points, ofi'ering theirresistance or leverage in diferent directions, in such a manner thatthose arches, having their curve pointing upward, receive their leveragein one direction, andthose having their curve pointing downward, receivetheir leverage in another direction; the reason for this lies again inthe necessity to create tW0 results in direc tions linear opposed toeach other, called for by the principle; it Will be evident that neversuch opposition can be obtained, When the arches were not provided withleverage in difieremt directions. This difierence in leverage forms orconstitutes another reason why the upper and lower arches cannot havepoints in which their material bodily wOuld be conjoined, for such apoint would cause a new leverage to spring forth, which would be a causefor the destruction of their individual original independent leverage.In fact a single bolt driven through their crossing points, wouldtotally destroy the com pensating qualities of the bridge; this Will beevident by the remarks oflered upon this subject; Which is strikinglyillustrative of the great difierence in the character of thiscompensating principle from other bridge principles, all of whichwithout exception conjoin and secure by all available means, thosepoints where parts of their materiil cross each other. The tension rodsdo not constitute pomts, in which the arches are bodily conjoined.

5. The arches are connected with the fioor in a special manner; thisspecial manner consists in the lower arches alone be directly tied andbraced to the fioor, which is only connected indirectly with the upperarches through the medium of the lower; in such a manner that the lowerarches a, b, c and (Z, are tied and braced to the fioor as shown in thedrawings, it being necessary to take special care not to bolt, brace,tie or 7 strap the 1qaperzwches A and B to the fioor,

in order that there be no direct connection, 1n no manner whatever,hetween the floor and said upper arches; the lower arches u, k

7), c and d, to be tied and braced to the upper arches A and B, as shownin the drawings, taking speoial care not to bolt, brace,

tie or strap or key them together in their crossing points. and not toallow any ten sion rod or brace between them, which would be farther outof the perpendicular position,than one inch in ten; such places betweenthe arches, where said slope would be more out of the perpendicularlime, ought to remain without. The tension rods between the arches, tobe normals on the curve of the upper arches A and B, also the braocsbetwe'en the arches outside their crossing points, to be normals on thesame curve. The position of the braces between the arches inside theircrossing points is immaterial to the compensating principle, and

-said braces may be removed after the process of securing the tensionrods (L) equally tight by their aid, is gone through. The object of thisspecial manner of connecting arches With arches, and arches with afioor, is to carry out and bring in applica tion those parts of theprinciple, which are described in the following terms see page 1 of thisspecificaon, While in the same time, said final results are caused to beperfectly equal in intensity the mechanical result of such forces, whentied together, is

' rest; they annihilate each other. The reason why the fioor is not tieddirectly to the upper and lower arches at the same .time, lies in theprinciple which rcquires that the strain should be divided in the upperand lower arches in order to create two compressed forces; it Will beevident that if the floor was tied directly to the upper and lowerarches at the same time, the necessary consequence would be, that eitherthe upper or the lower arches alone would take all the strain; owing tothe practical impossibility to tie both in such an equal manner that adivision of strain between them would take place.

T0 enable others skilled in the art to make and use rny invention, IWill add to this description of its nature the following practicalremarks.

The distance between the crossing points of the arches, in alongitudinal sense, should always be, between the limits, of not lessthan one third and not more than two thirds, of the span of the bridge.

In proportion that the curve used for the arches in the compensatingbridge is nearer the pure parabola, of which the parametcr is equal tofive times, half the span of the bridge, shall the result produced bemore efiectual, taking care to use the same curvaturc in theconstruction of all the arches.

There should be alfiays as many floor chords as there are 1oWer arches.

The compensating qualities et the bridge would be made nearly useless ifthe fioor is not less given to deflection than those in common use inbridge building. In proportion that the floor of the compensacing bridgeis less subject to defiection, in the same ratio Will the compensatingqualitics of the bridge offer a more satisfactory practical result.Therefore the fioor best adapted for the Compensacimg bridge Will besuch a one likc is represented on the drawings, which is constructed onthe Well known tubular principle, as used in the celebrated iron tubularbridge Britannia, constructed Over the Menai Straits by RobertStephenson, Esqr., C. E.

The fioor of the compensating bridge shown in the drawing consiscs in adouble range of.floor beams (Y), separated by the fioor chords, forminga hollow body, which is braced diagonally inside, by horizontal pieces,bolted togethcr vertically where they form crossing points with thebeams and witheach other. The ends of the floor should become longer asten feet, in whidrcase counter braces may be used to intersect theiriength.

The braces in the compensating bridge need not be so strong as those inother bridges, because they play only a secondary part in thecompensating bridge; that such is a fact becomes strikingly illustratedin observing that, by removing the braces in the compensating bridge,the bridge remains notwithstanding able to sustain a considerable load,however losing its compensating qualities; while removing the braces inother bridges actuafly destroys them as a bridge, s0 effectuaily chatwithont them they are not able to sustain their own weight of material.

' What I daim as my invention and desire to secure by Letters Patent is:

1. Thac combination of and between chose mechanical agencies andtechnical parts Which constitutes the herein described mode, to preventvibration in a bridge, by using the compensated effect of compressiononiy; as carried out and brought in appication, in the herein describedcompensating bridge. The term compensated eiect, as used here, does notmean the combined result of the forces, which are opposed andneutralized by each other; but is to be understood in the definitivesense of the following Words of our specification the medmnical resultof two forces, which are opposed t0 each other in direction, and equa1in intensity; when tied together.

2. I daim: The combination of and between: the mode in which the archesare arranged and cross each other; and the mode in which they areconnected with the fio01; and fina11y the mode in which they receivetheir leverage; as herein described; tire mechanical efiect of whichsaid combination is, to originate The tendencies in the upper and lowerarches to curve apart or asunder.

3. I daim: The combination of and be tween: the mode in which the archescross each other; and the mode in which they are connected with thefioor; and the mode fina1ly'in which they are constructed in regard t0amount of material; as herein described; the mechanical effect of whichsaid combination is, to originate the equai in* tensity of the saidtendencies.

4. I daim: The employ, in bridge construction, of the herein describedarches, arranged and connected as described, as a practical snbstitntefor npper chords, and generally for all such parts in bridges, whichserve to uphold the fioor.

5. I daim: The special mode, in the herein described arches, areconnected with the floor.

G. W. O. IIUYGENS. VVitnesses:

J AS. A. CONWAY, JOHN FLYNN.

